Which is a pretty bad idea if you want to invoke the wrath of God. The first Temple was built in 996 B.C. and destroyed in 587 B.C. by Nebuchadnezzar II of Babylon to crush the Jewish revolt. The second Temple was built in 530 B.C. and destroyed again by Emperor Titus (no relation) in A.D. 70 to crush another Jewish revolt.

This was foretold by Jesus:

Jesus left the temple and was going away, when his disciples came to point out to him the buildings of the temple. But he answered them, "You see all these, do you not? Truly, I say to you, there will not be left here one stone upon another, that will not be thrown down." As he sat on the Mount of Olives, the disciples came to him privately, saying, "Tell us, when will this be, and what will be the sign of your coming and of the close of the age?" And Jesus answered them, "Take heed that no one leads you astray. For many will come in my name, saying, `I am the Christ,' and they will lead many astray. And you will hear of wars and rumors of wars; see that you are not alarmed; for this must take place, but the end is not yet. --Holy Gospel of St. Matthew 24:1-6

Catholic Tradition states that Jesus is the new (third) Temple. And any reference to a material 'third Temple' is just a sign of the second coming of Christ. Though Protestants make the third Temple a significant portion of their theology, Catholics say it only in passing. Thus why many Protestants are pushing for the rebuilding of the third Temple. Thinking they can manipulate events to 'force' the return of Jesus. How mistaken they are.

You cannot tempt God.

Emperor Julian of the Roman Empire, commonly known as Julian the Apostate, being the last pagan ruler of Roman Empire knew very well how to undermine Christianity. He set about in A.D. 363 to rebuild the third Temple in order to mock the Christians of Palestine. His contemporary, the last great pagan historian, Ammianus Marcellinus, described Emperor Julian's attempt at rebuilding the third Temple by commissioning a Project Manager in Alypius. Even when an earthquake struck, Alypius pushed on with Emperor Julian's project:

Though Alypius pushed the work forward energetically and though he was assisted by the governor of the province, frightful balls of fire kept bursting forth near the foundations of the temple and made it impossible for the workmen to approach the place, and some were even burned to death. And since the elements persistently drove them back, Julian gave up the attempt.

'Frightful balls of fire kept bursting forth near the foundations of the temple', secular revisionist historians downplay the significance that God was involved by pushing their theory that Christian arsonists were involved. Nonetheless, the point is made that you cannot tempt God and get away with it.

So the many Protestant Christian's that are funding and pushing for the building of the third Temple are they themselves playing with 'fire', pun intended.

To read the homilies of St. John Chrysostom regarding the second coming click here and here.